Bone fractures are typically treated by restoring the fractured pieces of bone to their natural positions and maintaining those positions while the bone heals. Briefly, the fractured bone(s) is aligned in good position (also called reduction) and then immobilized with a cast that holds the bones in position and immobilizes the joints above and below the fracture. When the initial post-fracture edema or swelling goes down, the fracture may be placed in a removable brace or orthosis. In cases of complex or open fractures, surgical nails, screws, plates and wires may be used to internally hold the fractured bone together. The surgical implantation of these internal fixation devices, however, may cause extensive trauma to the patient, increase potential for infection, and require second surgery for their removal. An alternative to internal fixation devices is the external fixation device. Pins are placed into the broken bone above and below the fracture site to reposition and immobilize the bone fragments. The pins are connected to a metal bar or bars outside the skin to form a stabilizing frame that holds the bones in the proper position so they can heal. After an appropriate period of time, the external fixation device is removed.
The proximal humerus is part of the shoulder joint, and it also is the attachment of the important rotator cuff muscles. These muscles help with movement of the shoulder, and injury to the proximal humerus can affect the function of these muscles. A proximal humerus fracture is a common injury to the shoulder and are among the most common broken bones. It is not possible to immobilize proximal humerus fractures by placing them in a cast. There still exists a need for lightweight, non-bridging external fixation devices that allows for direct fixation of a proximal humerus fracture, maintenance of the radiological parameters, and early mobilization of the shoulder.